If your St. Louis tap water tastes or smells different on the hot side than on the cold side, that difference is worth noticing before you buy any filtration. Taste and smell cannot tell you everything that is in your water, but they can point you toward the right checks and help you describe the problem clearly to a tester or plumber.
Start with a side-by-side taste
Fill two clean glasses, one from the cold kitchen tap and one from the hot kitchen tap, and taste them one after the other. Write down what you notice, such as a metallic taste, a flat taste, a chlorine smell, a sulfur smell, or no difference at all. Choose a time when no one has just run the dishwasher or washing machine, since those appliances can change what comes out of the faucet for a while.
Repeat the test at a second tap in the house, such as the bathroom sink. Compare your notes. The pattern tells you where to look next.
If only the hot water tastes off
A taste or smell that appears only on the hot side usually points to the water heater or the hot water piping. Sediment can settle at the bottom of a tank water heater over time, and it can carry an odor into the hot line. Hot water can also pull more metal from some older plumbing than cold water does. Look for rust-colored or grit-like material in a glass of hot water, and note whether the problem gets better after you run the hot tap for a while.
If you see sediment or the smell persists, have a licensed plumber inspect the water heater. Do not open gas or electric controls yourself unless you have the training and the manufacturer instructions to do it safely.
If the cold side is the problem
A taste that appears on the cold side points to the cold supply or to something installed on that line. Check whether you already have a filter, softener, or other treatment device on the cold feed. Find its service date and note whether the cartridge or media is overdue for replacement. An old filter can hold on to odors and release them later.
Also check whether the taste appears only at the kitchen cold tap or at every cold tap in the house. If every cold tap shows the same problem, the issue is more likely in the supply or the main line than in one fixture.
Run a simple house-wide check
- Taste the cold water at the kitchen, bathroom, and any outdoor or laundry tap.
- Taste the hot water at the same fixtures.
- Look for a pattern: same at every tap, only hot, or only one location.
- Check for recent work, such as a water heater replacement, a plumbing repair, or a change in the treatment equipment.
- Record the date, the time of day, and what you noticed, so you can compare later.
Get a lab sample before you decide
Taste tests can narrow a problem, but they cannot identify specific substances. A certified laboratory can test a water sample for the items you are concerned about. Ask the lab which tests it offers, how it collects the sample, and how long results usually take. Labs often provide instructions for filling the sample container so the result reflects what comes out of your tap.
For the St. Louis supply, your water provider publishes information about its treated water, and you can ask for it before you test your home. Compare the provider information with your own sample results. The two together give you a clearer picture than either one alone.
Questions to answer before choosing reverse osmosis
- Does the taste or smell appear on both the hot and cold sides, or on only one?
- Is the problem at one fixture or throughout the house?
- Has the water heater, plumbing, or any existing filter been serviced recently?
- Do you have a lab result that names the substance you want to address?
- Would a filter placed at one tap solve your problem, or does the issue start upstream of the kitchen?
Reverse osmosis is one option for drinking and cooking water at a single tap, but it does not fix problems that start in a water heater or in the distribution piping. Answer the questions above first, so the equipment you choose matches the problem you actually have.